1. Field of the Invention
This invention relates to a bio-chemical engineering process. More particularly, this invention relates to a process by which spent antibiotic fermentation broth containing relatively high concentrations of fatty and proteinaceous material can be treated to reduce the biological oxygen demand of the effluent therefrom to a level that meets the requirements of the Environmental Protection Agency for waste water being discharged into the environment.
2. Description of the Prior Art
Over the past centuries processes involving fermentations utilizing microorganisms have been used all over the world. Perhaps the earliest example of this, which has come down to us from antiquity, has been the fermentation of carbohydrates to produce alcoholic beverages. Little more need be said about that.
In the past three or four decades another very important application of the fermentation process has been the production of useful antibiotics. Beginning with the development of the submerged culture technology for the preparation of penicillin, there has been a great proliferation of antibiotics useful not only for curing a wide variety of infectious ills of mankind, but also in the field of animal husbandry and animal nutrition. As the development of these many antibiotics has gone forward, large numbers of diverse organisms have been found which, when grown in a suitable media, provide useful products. And, as this development has proceeded, a wide range of problems have been encountered in the disposal of the waste from such operations.
In the culture of the microorganisms for the production of antibiotics all sorts of nutritive agents have been identified as useful in promoting the growth of such organisms. Moreover, techniques have been established which often result in an abundance of residual materials in the spent broth, most of which are organic in nature and must be disposed of by means other than simply discharging the waste into the sewer or directly to the environment.
Many of the useful antibiotic materials available today have been produced by growing the microorganism in media rich in both fats and proteins. The presence of these nutrients in the fermentation broth in which the antibiotic is produced has resulted in spent broth having relatively high concentrations of fats and/or proteins and their residues. Biological degradation of these residues in the spent broth is slow and costly.
One spent antibiotic fermentation broth which is illustrative of the broth wherein the residual fats and proteins and their fragments are considered to be relatively high is that of the antibiotic monensic acid from the fermentation of the microorganism Streptomyces cinnamonensis. In this fermentation procedure, a wide variety of materials are used, and produced as metabolites in the culture, which can be identified as fats. Furthermore, there are residual proteins and fragments of proteinaceous material carried over in the broth in which the monensic acid is produced and from which such acid is recovered as a useful antibiotic. Monensic acid is being widely utilized throughout the world as an exceptionally active coccidiostat. Frequently spent fermentation broth from which monensic acid is isolated has been found to contain fats to the extent of as much as 11 percent before, and four percent after primary recovery. The residual proteinaceous content runs in the neighborhood of one percent.
For the purpose of this invention fats may be described as any monocarboxylic acid of more than 2 carbon atoms in length whether as a free acid or in the form of a mono-, di-, or tri-, glyceride. Proteinaceous material is generally recognized as being those organic compounds which are comprised of a number of amino acids assembled by nature in a predetermined orientation.
The conventional and classic means for disposing of spent fermentation broth from which essentially all of the antibiotic has been isolated has followed the route of a pH-adjustment to from about 8.0 to 9.0, slurrying with such pH-adjusted spent broth a quantity of either aerobic or anaerobic activated sludge, vigorously agitating such slurry for an extended period of time, clarifying such activated sludge containing spent broth by allowing the slurry to settle for 2 to 4 hours or more and then decanting the supernatant from the clarification operation and again artificially aerating such supernatant to further reduce the biological oxygen demand to a suitable level before discharging the waste into the environment.
The employment of such a process requires large size equipment, a long period of time, a substantial energy input in the artificial aeration of the supernatant and a reasonably high cost due to the materials handling and power requirements.
Accordingly, it is an object of the instant invention to provide a process which will be simple, uncomplicated, low in cost, and workable with a minimum of equipment and energy input to reduce the concentrations of the residual fats and proteinaceous material in a spent antibiotic fermentation broth to a level wherein the biological oxygen demand of the effluent from such process meets the requirements of the Environmental Protection Agency of no more than a biological oxygen demand of 0.04 g. oxygen per liter.